Halogen Lamp

Abstract

A halogen lamp is described that is intended in particular for at least one mode of operation at a lamp voltage substantially below the nominal voltage or a lamp power substantially below the nominal power or that is intended for switching between a first such mode of operation and a second, normal mode of operation in which the lamp is operated substantially at its nominal voltage or power. To prevent, in the first mode of operation, any increased mass transport of molybdenum and, as a result of this, possible blackening of the envelope of the lamp or growth of whiskers in the region of the legs of the incandescent filament or of the first turns of the incandescent filament, use is made of a bromine-free filling gas that has chlorine. Lamps of this kind are used for example in the headlights of motor vehicles for what is termed daylight running (DRL=daylight running light).

1 . A halogen lamp that is intended in particular for at least one mode of operation at a lamp voltage substantially below the nominal voltage or at a lamp power substantially below the nominal power or that is intended for switching between a first such mode of operation and a second, normal mode of operation in which the lamp is operated substantially at its nominal voltage or power, the lamp having an at least substantially bromine-free filling gas having at least one inert gas and at least one halogen in the form of chlorine. 
   
   
       2 . A halogen lamp as claimed in  claim 1 , in which the filling gas comprises an inert gas and chlorine as a halogen in an amount of between approximately 100 ppm and approximately 200 ppm. 
   
   
       3 . A halogen lamp as claimed in  claim 1 , in which the pressure of the filling gas in the envelope of the lamp is between approximately 10 and approximately 15 bars. 
   
   
       4 . A halogen lamp as claimed in  claim 1 , in which the lead wires ( 3 ,  4 ) to an incandescent filament ( 2 ) are made of molybdenum. 
   
   
       5 . A halogen lamp as claimed in  claim 1 , in a design for use in headlights of motor vehicles. 
   
   
       6 . A halogen lamp as claimed in  claim 5 , in a design as an H7 lamp for a DRL application.